Torque/position transducer

ABSTRACT

A torque/position transducer is positioned between the valve stem of a valve and a valve operator adapted to open and close the valve and includes a body section including an input lug adapted for mating the engagement with the output lug of the valve operator and an output lug adapted for mating the engagement with the valve stem of the valve. A pair of strain gauges are mounted on the body of the torque/position transducer and function to generate an output signal indicative of the amount of torque necessary to open or close the valve. The body further includes a cam secured to the body section. A magnet is positioned in movable contact with the cam. A magneto-resistive sensor senses the movement of the magnet as the cam varies the distance from said magnet to said sensor and generates a signal indicative of the position of the valve stem with respect to the valve under the action of the valve operator.

RELATED APPLICATION

This application is a continuation-in-part of application Ser. No.08/374,846, filed Jan. 19, 1995, which is now U.S. Pat. No. 5,524,485.

TECHNICAL FIELD

The present invention relates generally to torque/position transducersand, more particularly, to a unique torque/position transducer that isparticularly adapted for use in conjunction with valves and operatorstherefore.

BACKGROUND AND SUMMARY OF THE INVENTION

At the present time, valves such as those employed in petroleumpipelines and the like are typically not manually operated. Rather, suchvalves are opened and closed utilizing valve operators. Valve operatorsfor pipeline valves typically comprise an electric or fluid operatedmotor and a speed reducer which operate in combination to provide theoutput torque necessary to open and/or close the valve.

It has been determined that the torque necessary to open or close avalve is indicative of the operating condition of the valve. It is,therefore, useful to measure the torque necessary to operate the valveas a function of the operational status of the valve which in turnpredicts the time remaining before the valve must be either serviced orreplaced. The measurement of the torque necessary to operate the valveis a function of the positioning of the valve, with the highest torquerequirement usually occurring at the start of the valve opening orclosing operation.

SUMMARY OF THE INVENTION

The present invention comprises a torque/position transducer which islocated between the valve operator and the valve stem of a valve andwhich functions to generate an output indicative of the torque necessaryto open or close the valve and the positioning of the valve when thetorque measurement is made.

The torque/position transducer comprises a body including an input lugwhich mates with the output lug of the valve operator and an output lugwhich mates with the valve stem of the valve to be opened or closed. Apair of strain gauges are mounted on the body of the torque/positiontransducer and function to generate an output signal indicative of theamount of torque necessary to open or close the valve. The body furtherincludes a cam secured to the body section. A magnet is positioned inmovable contact with the cam. A magneto-resistive sensor senses themovement of the magnet as the cam varies the distance from said magnetto said sensor and generates a signal indicative of the position of thevalve stem with respect to the valve under the action of the valveoperator.

BRIEF DESCRIPTION OF DRAWINGS

A more complete understanding of the present invention may be had byreference to the following Detailed Description when taken inconjunction with the accompanying Drawings, in which:

FIG. 1 is a side view of a first embodiment of a torque/positiontransducer incorporating the present invention shown in its operatingenvironment;

FIG. 2 is a top view of the body of the torque/position transducer ofFIG. 1;

FIG. 3 is a side view of the body of FIG. 2;

FIG. 4 is a longitudinal sectional view of the body of FIG. 2;

FIG. 5 is a bottom view of the body of the FIG. 2;

FIG. 6 is a side view of one of the interlocking rings of thetorque/position transducer of FIG. 1;

FIG. 7 is a top view of the interlocking ring of FIG. 6;

FIG. 8 is a sectional view of a second interlocking ring of thetorque/position transducer of FIG. 1;

FIG. 9 is top view of the interlocking ring of FIG. 8;

FIG. 10 is a perspective view of the torque/position transducer of thepresent invention in which the component parts thereof are shown in alongitudinally exploded orientation;

FIG. 11 is a side view of a second embodiment of a torque/positiontransducer incorporating the present invention shown in its operatingenvironment;

FIG. 12 is a perspective view of the body section of the torque/positiontransducer of FIG. 11;

FIG. 13 is a section view of the second embodiment of a torque/positiontransducer of the present invention;

FIG. 14 is a section view of the body section of the torque/positiontransducer of FIG. 13;

FIG. 15 is a bottom view of the body section of the torque/positiontransducer of FIG. 14;

FIG. 16 is a top view of the body section of the torque/positiontransducer of FIG. 15;

FIG. 17 is a top view of the cam located on the body section of thetorque/position transducer of FIG. 15;

FIG. 18 is a schematic of the torque transmitter circuit of the presentinvention; and

FIG. 19 is a schematic of the position transmitter circuit of thepresent invention.

DETAILED DESCRIPTION

Referring now to the Drawings, and in particular to FIG. 1 thereof,there is shown a torque/position transducer 20 incorporating the presentinvention. In FIG. 1, the torque/position transducer 20 is shownoperably connected between a valve 30 and a valve operator 40. The valve30 is positioned in a pipeline 32 and comprises a valve body 34. Thevalve contained within the valve body 34 is actuated by a valve stem 36extending from a packing housing 38 at the upper end of the valve body34.

The valve operator 40 comprises a motor 42 which may be either manual,electric or fluid operated. Typically, the motor 42 will behydraulically driven. The motor has an output which is operablyconnected to a speed reducer 44. The speed reducer 44 in turn drives adrive lug 46. The valve operator 40 is supported above the valve 30 on abracket 48.

Referring now to FIG. 10, the torque/position transducer 20 of thepresent invention comprises a body 22 and a pair of interlocking rings24 which are ordinarily telescopingly received around the body 22. As isbest shown in FIGS. 2 through 5, the body 22 of the torque/positiontransducer 20 includes an upper input lug 52 which is square incross-section. The lug 52 extends to a flange 54 which in turn extendsto a cylindrical section 56. The cylindrical section 56 has a pluralityof strain gauges 58 mounted thereon.

The torque/position transducer 20 comprises a plurality of strain gauges58 mounted at spaced apart locations around the periphery of thecylindrical section 56 of the body 22. The strain gauges 58 arepreferably angularly disposed relative to the axis of the body 22, andan orientation of 45 degrees with respect to the axis of the body 22 ispreferable. Each of the strain gauges 58 has a pair of output leads 60which are directed from the strain gauge to appropriate circuitry whichis used to combine and average the output of the several strain gauges58 comprising the torque/positioning transducer 20 to provide an outputindicative of the torque applied thereto.

The cylindrical portion 56 of the body 22 extends to a second flange 62which in turn extends to an output lug 64. In the normal usage of thetorque/positioning transducer 20, the lug 52 is engaged with the drivelug 46 of the valve operator 40, and the lug 64 is engaged with thevalve stem 36 of the valve 30. Thus, the body 22 functions to transfertorque from the valve operator 40 to the valve 30.

As will be apparent, to the extent the drive lug 46 of the valveoperator 40 rotates in advance of the valve stem 36 of the valve 30, thebody 22 of the torque/positioning transducer 20 is distorted. Anydistortion of the body 20 results in deformation of the strain gauges 58which in turn causes strain gauges 58 to generate a variance in voltage.The strain gauges 58 produce a very small change in voltage which isamplified to produce a one to five volt signal. The one to five voltsignal is then converted to a four to twenty milliamp signal which iscompatible with industrial standards for electronic control andmeasuring devices. At rest, the signal produced is twelve milliamps.This is the mid point between four and twenty milliamps. A signalgreater than twelve milliamps represents torque that is measured whenthe valve stem is rotated in a clockwise direction and a signal lessthan twelve milliamps represents torque measured when the stem isrotated in a counterclockwise direction.

It will thus be understood that the strain gauges 58 attached to thecylindrical section 56 of the body 22 of the torque/position transducer20 generate an output signal which is indicative of the angulardifferentiation between the valve operator 40 and the valve 30 as thevalve operator 40 is actuated to either open or close the valve 30. Suchmeasurement is in turn indicative of the operating condition of thevalve. Thus, by monitoring the torque necessary to open or close thevalve, the necessity of repair or replacement of the valve at apredetermined period of time can be determined.

The interlocking rings 24 of the torque/position transducer are bestshown in FIGS. 6-9. A moving ring 70 is engaged with input lug 52 of thebody 22 by means of a light press fit. Thus, the ring 70 is fixed to thelug 52 and is not permitted to rotate with respect thereto, but rathermoves with the body 22.

Referring to FIG. 10, the ring 70 has an aperture 72 formed therein. Theaperture 72 extends to an armored cable 74 which is used to carry leads60 from the strain gauges 58 outwardly to circuitry connected theretoand adapted to process the voltage changes caused in the strain gauges58 by the application of torque to the body 22. The aperture 72 and thearmored cable 74 also direct electrical leads 75 to an infrared lightgenerator 76 and an infrared light detector 78 mounted on the interiorof the moving ring 70. The infrared light generator 76 directs infraredenergy through an aperture 80 formed in the ring 70, and the infraredlight receiver 78 receives reflected light received back through anaperture 82 formed therein.

The moving ring 70 has a reduced diameter portion 84 extendingdownwardly therefrom. A fixed ring 86 is slidably received on thereduced diameter portion 84 of the moving ring 70 and has a lug 88projecting therefrom. The interior of the ring 86 is provided with afoil layer 90.

As is best shown in FIG. 8, the foil layer 90 of the fixed ring 86 has areflective portion 92. The reflective portion 92 and a non-reflectiveportion 94 cooperate to form a divergent reflective surface on theinterior of the fixed ring 86. Thus, the amount of infrared energydirected on the foil layer 90 from the source 76 and reflected backtherefrom onto the receiver 78 is dependent on the relative positioningof the fixed ring 86 relative to the moving ring 70.

Referring again to FIG. 1, a bracket 100 extends downwardly from thevalve operator 40 and into engagement with the lug 88 extending from thefixed ring 86. The bracket 100 functions to prevent the fixed ring 86from rotation relative to either the valve 30 or the valve operator 40in either direction. Since the moving ring 70 is secured to the inputlug 52 of the body 22 of the torque/position transducer 20, it isconstrained to movement therewith. Therefore, as the valve 30 is openedor closed, the relative positioning of the ring 70 and the ring 86 isdetermined by the amount of infrared energy reflected back from the foillayer 90 of the fixed ring 86 to the receiver 78 mounted on the interiorof the moving ring 70.

Referring now to FIG. 11 therein is illustrated a second embodiment ofthe present invention. The torque/position transducer 120 is shownoperably connected between a valve 130 and a valve operator 140. Thevalve 130 is positioned in a pipeline 132 and comprises a valve body134. The valve contained within the valve body 134 is actuated by avalve stem 136 extending from a packing housing 138 at the upper end ofthe valve body 134.

The valve operator 140 comprises a motor 142 which may be either manual,electric or fluid operated. Typically, the motor 142 will behydraulically driven. The motor 142 has an output which is operablyconnected to a speed reducer 144. The speed reducer 144 in turn drives adrive lug 146.

Referring now to FIGS. 12-17, the torque/position transducer 120 of thepresent invention comprises a body 122 including an upper input lug 152which is square in cross-section. The lug 152 extends to a flange 154that in turn extends to an integral cam 155. Adjacent to the cam 155 isa cylindrical section 156. The cylindrical portion 156 of the body 122extends to an output lug 164. Output lug 164 includes a square opening165 for receiving valve stem 136.

Cylindrical portion 156 includes a pair of 350 ohm strain gauges 158mounted thereon. The strain gauges 158 are connected in a bridgeconfiguration spaced 180 degrees apart on the cylindrical section 156.Each of the strain gauges 158 has a pair of output leads 160 that areconnected to circuit board 180. Referring now to FIG. 18, a torquetransmitter circuit diagram is disclosed wherein the output signal isconverted to a 4 to 20 milliamp signal indicative of the torque applied.

In the normal usage of the torque/positioning transducer 120, the lug152 is engaged with the drive lug 146 of the valve operator 140, and thelug 164 is engaged with the valve stem 136 of the valve 130. Thus, thebody 122 functions to transfer torque from the valve operator 140 to thevalve 130.

As will be apparent, to the extent the drive lug 146 of the valveoperator 140 rotates in advance of the valve stem 136 of the valve 130,the body 122 of the torque/positioning transducer 120 is distorted. Anydistortion of the body 120 results in deformation of the strain gauges158 which in turn causes strain gauges 158 to generate a variance involtage. The strain gauges 158 produce a very small change in voltagewhich is amplified to produce a one to five volt signal. The one to fivevolt signal is then converted to a four to twenty milliamp signal whichis compatible with industrial standards for electronic control andmeasuring devices. At rest, the signal produced is twelve milliamps.This is the mid-point between four and twenty milliamps. A signalgreater than twelve milliamps represents torque that is measured whenthe valve stem is rotated in a clockwise direction and a signal lessthan twelve milliamps represents torque measured when the stem isrotated in a counterclockwise direction.

It will thus be understood that the strain gauges 158 attached to thecylindrical section 156 of the body 122 of the torque/positiontransducer 120 generate an output signal which is indicative of theangular differentiation between the valve operator 140 and the valve 130as the valve operator 140 is actuated to either open or close the valve130. Such measurement is in turn indicative of the operating conditionof the valve 130. Thus, by monitoring the torque necessary to open orclose the valve, the necessity of repair or replacement of the valve ata predetermined period of time can be determined.

Referring to FIGS. 12, 13 and 17 therein is illustrated cam 155 andvalve position sensor 170. As illustrated in FIG. 17 cam 155 has varyingradial dimensions expressed in inches, R1=1.63839; R2=1.64547;R3=1.75942; R4=1.86792; R5=1.90643; R6=1.90650; R7=1.96651; R8=1.688.The proximal end of the leaf spring 172 is affixed to a base 202 ofhousing 200. The distal end of leaf spring 172 includes a magnet 174that is kept in position against cam 155. As valve 130 is operated cam155 varies the distance for the magnet 174 to sensor 170. Turning now toFIG. 19, Valve position sensor 170 includes a NVE NVSSB100magneto-resistive sensor, that outputs a very small change in voltagewhich is amplified to produce a one to five volt signal. The one to fivevolt signal is then converted to a four to twenty milliamp signal whichis compatible with industrial standards for electronic control andmeasuring devices.

When assembled, body section 122 is partially enclosed in housing 200.Lug 152 extends from the top 204 of housing 200. Flange 154 is receivedin a circular opening in the top 204 of housing 200. Bushing 190 andseals 192 are positioned around body section 122 and received in thecircular opening in the top 204 of housing 200. Output lug 164 extendsthrough a circular opening in the bottom 202 of housing 200. Bushing 194and seal 196 are positioned around body section 122 and received in thecircular opening in the bottom 202 of housing 200.

OPERATION

In the operation of the first embodiment of the present invention, thetorque/position transducer 20, the valve operator 40 is actuated toeither open or close the valve 30. Depending on the condition of thevalve 30, significant lag may occur between the drive lug 46 and thevalve stem 36, resulting in significant deformation of the body 22 ofthe torque/position transducer 20. Any deformation to the body 22 causesdeflection of the strain gauges 58 which in turn generates an electricaloutput that is transferred to external circuities through the aperture72 and the armored cable 74 attached to the fixed ring 70.

As the valve operator 40 rotates the valve stem 36 to open or close thevalve 30, the moving ring 70 moves with the valve body 20, while thefixed ring 86 is locked in place by the inter-engagement of the lug 88with the bracket 100. Infrared energy generated by the generator 76 onthe moving ring 70 is reflected onto the foil layer 90 and is reflectedback therefrom to the receiver 78. The amount of energy reflected backto the receiver 78 is dependent on the amount of the reflective portion92 of the foil layer 90 which is exposed from the energy from thegenerator 76. Thus, the receiver 78 provides an output indicative of thepositioning of the valve 30 at the time that any particular torqueoutput is recorded.

In the operation of the second embodiment of the present invention, thetorque/position transducer 120, the valve operator 140 is actuated toeither open or close the valve 130. Depending on the condition of thevalve 130, significant lag may occur between the drive lug 146 and thevalve stem 136, resulting in significant deformation of the body 122 ofthe torque/position transducer 120. Any deformation to the body 122causes deflection of the strain gauges 158 which in turn generates anelectrical output.

As the valve operator 140 rotates the valve stem 136 to open or closethe valve 130, cam 155 moves magnet 174 closer or farther from positionsensor 170 which in turn generates an electrical output indicating theposition of valve 130 at the time that any particular torque output isrecorded.

Although preferred embodiments of the invention have been illustrated inthe accompanying Drawings and described in the foregoing DetailedDescription, it will be understood that the invention is not limited tothe embodiments disclosed, but is capable of numerous rearrangements andmodifications without departing from the spirit of the invention.

We claim:
 1. An apparatus for determining the torque applied by a valveactuator to a valve stem,said valve having a valve stem with a valvestem input lug, said valve actuator having a valve actuator output lug,said apparatus for determining the applied torque comprising:a. arotatable body having:an upper input lug mated to the valve actuatoroutput lug, a lower output lug mated to the valve stem input lug, and acylindrical central body portion connecting the upper input lug and thelower output lug; b. at least two strain gauges mounted on saidcylindrical central body portion; and c. means responsive to the outputsignal from said strain gauge for generating a signal indicative of thetorque applied to the valve by the valve operator.
 2. The apparatus fordetermining the torque applied by a valve actuator to a valve stem ofclaim 1 wherein the at least two strain gauges are mounted on thecylindrical body portion 180 degrees apart and are bridge connected. 3.The apparatus for determining the torque applied by a valve actuator toa valve stem of claim 1 further including a circuit board that convertsthe output of the strain gauges to a four to twenty milliamp outputsignal indicative of the torque applied by the valve actuator to thevalve stem.
 4. An apparatus for determining the position of a valve stemwith respect to a valve being operated responsive to a valveactuator,said valve having a fixed valve body, a rotatable valve stemattached to a valve stem input lug, said valve actuator having a valveactuator output lug, said apparatus for determining the position of avalve stem comprising:a. a rotatable body including:an upper input lugmated to the valve actuator output lug, a lower output lug mated to thevalve stem input lug, and a cylindrical body portion connecting theupper input lug and the lower output lug; b. a cam secured to saidcylindrical body portion for rotation therewith, said cam including:anexterior side disposed away from the cylindrical body; c. a magnetpositioned in movable contact with the exterior side of said cam; and d.means responsive to the position of said magnet for generating a signalindicative of the position of the valve stem with respect to the valve.5. The apparatus for determining the position of a valve stem withrespect to a valve of claim 4 wherein the means responsive to theposition of said magnet for generating a signal indicative of theposition of the valve stem with respect to the valve is amagneto-resistive sensor that senses the movement of the magnet as thecam varies the distance from said magnet to said sensor.
 6. Theapparatus for determining the position of a valve stem with respect to avalve of claim 5 further including a circuit board that converts theoutput of the magneto-resistive sensor to a four to twenty milliampoutput signal indicative of the position of the valve stem with respectto the valve.
 7. An apparatus for determining the torque applied by avalve actuator to a valve stem at a particular position of the valvestem with respect to the valve,said valve having a fixed valve body, arotatable valve stem attached to a valve stem input lug, said valveactuator having a valve actuator output lug, said apparatus fordetermining the position comprising:a. a rotatable body having:an upperinput lug mated to the valve actuator output lug, a lower output lugmated to the valve stem input lug, and a cylindrical central bodyportion connecting the upper input lug and the lower output lug; b. atleast two strain gauges mounted on said cylindrical central bodyportion; c. means responsive to the output signal from said strain gaugefor generating a signal indicative of the torque applied to the valve bythe valve operator; d. a cam secured to said cylindrical body portionfor rotation therewith, said cam including:an exterior side disposedaway from the cylindrical body; e. a magnet positioned in movablecontact with the exterior side of said cam; and f. means responsive tothe position of said magnet for generating a signal indicative of theposition of the valve stem with respect to the valve.